Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Wind turbine with liquid medium distribution system
The invention describes a wind turbine comprising a tower, a
nacelle, a main shaft, a hub with blades, and a liquid medium
distribution system for transport of liquid medium in the
wind turbine. The invention further describes a method of
transporting liquid medium in a wind turbine and a use of a
liquid medium distribution system in a wind turbine.
Liquid media may be transported in a wind turbine for a
number of reasons. For example, a liquid medium may be part
of a heating-system for the wind turbine or for other parts
of the wind turbine.
US 7,168,251 discloses a wind energy turbine with a unit to
be cooled by a cooling medium (gas or liquid) flowing in a
cooling circuit from said unit to a heat exchanger. The unit
to be cooled is arranged in the tower or in the nacelle of
the wind energy turbine. The heat exchanger is located
outside of the tower or the nacelle and is configured to be
cooled by ambient air. In one embodiment, the cooling
components are used in a closed-loop cooling circuit with a
liquid cooling medium, for example water. A pump or similar
element is also arranged in the cooling circuit.
US 6,520,737 discloses an offshore wind turbine, wherein a
power transmission in a nacelle is cooled by means of a
liquid conducted to the nacelle from a tower on which the
nacelle is pivotally arranged around a vertical yawing axis.
A device is shown for forming one or more passageways for
liquid between the nacelle and the tower during most yaw
positions of the nacelle.
Regarding other liquids, in particular any liquid medium
required in the hub, for example lubricating oil for use in
bearings or hydraulic systems, liquids for blade defrosting
etc., in the prior art such liquid media are only transported
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intermittently in batches. A liquid medium is first stored in
a transport vessel or container, lifted into the nacelle by
cranes or hoists and manually distributed there by
maintenance staff. Obviously, such a manual distribution of
the liquid media is time-consuming and expensive.
Therefore, it is an object of the invention to provide a wind
turbine with an improved system for transport of liquid media
and accordingly to provide an improved method of transporting
liquid media in a wind turbine.
The object of the invention is achieved by a wind turbine
according to claim 1, by a method of transporting liquid
medium in a wind turbine according to claim 13 and by a use
of a liquid medium distribution system according to claim 15.
A wind turbine according to the invention comprises a liquid
medium distribution system with
a first distribution sub-system located in the tower;
a second distribution sub-system located in the nacelle;
a third distribution sub-system located in the hub;
a tower-nacelle-interface connecting the first distribution
sub-system to the second distribution sub-system, and a
nacelle-hub-interface connecting the second distribution sub-
system to the third distribution sub-system.
The favourable arrangement of the liquid medium distribution
system allows a transport of a liquid medium to desired
locations which may be located anywhere in the wind turbine.
The arrangement of the first, second and third distribution
sub-systems, together with the tower-nacelle-interface and
the nacelle-hub-interface, allow an effective distribution of
the liquid media, meeting also requirements of a distribution
via the two main rotating interfaces (tower-nacelle and
nacelle-hub) in a wind turbine to the hub. Compared with
prior art solutions, liquid media can be continually supplied
to any part of the wind turbine, instead of only
intermittently. The liquid medium is provided in a
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comfortable manner where, when and how it is needed. As a
favourable consequence, periods of idleness of the wind
turbine in order to perform regular maintenance works can be
minimized. Maintenance tasks are simplified and speeded up.
Therefore, by means of the liquid medium distribution system,
a continuous flow of liquid medium is possible, which
advantageously allows - despite a drastically reduced rate of
maintenance with regard to common wind turbines - a
continuous and substantially failure-free operation of the
wind turbine according to the invention. In other words, a
profitability of a wind turbine with the liquid distribution
system according to the invention can advantageously be
enhanced to a considerable extent.
Hereinafter, for the sake of clarity, the expression
"connecting" with regard to the liquid distribution system
means a functional coupling of diverse items, which coupling
enables a flow of liquid medium within the wind turbine.
Particularly advantageous embodiments and features of the
invention are defined in dependent claims, as revealed
hereinafter. Features of the various embodiments described
may be combined as appropriate.
A preferred embodiment of the wind turbine according to
the invention is characterized in that the first, the second
and the third distribution sub-systems each comprise a pipe
and optionally at least one of the following items: a pump, a
reservoir, a valve for regulating flow of the liquid medium,
a heat exchanger for heating and/or cooling the liquid
medium. These allow numerous ways in which the liquid medium
can be transported, stored, accessed and regulated in its
flow throughout the whole wind turbine or through parts of
it. The items mentioned can selectively be arranged at
desired locations in the tower, and/or in the nacelle, and/or
in the hub. Thus, an individual adaptation of the liquid
medium distribution system to real requirements of the liquid
media in the wind turbine is possible.
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The tower-nacelle-interface may be realized similar to the
cooling fluid system in the US 6,520,737. However, to allow a
yawing of the nacelle relative to the tower, the electric
connections from components in the nacelle to the tower is
often realized via cables having a suitable length such that
the nacelle may rotate, driven by motor or by the incoming
wind, several times around the yawing axis. In an initial
position of the nacelle the cables exhibit a sag and the
cable twists further with each turn of the nacelle until the
cable is too short to allow a further turn. Then, the nacelle
is returned to the initial position using a motor driven by
an appropriate controlling unit. In a cost-effective, and
therefore preferred, embodiment of the invention the tower-
nacelle-interface of the liquid medium distribution system of
the wind turbine comprises a flexible hose with a sag,
wherein an amount of the sag is dimensioned in accordance to
a length of at least an electric cable running from the tower
into the nacelle. In this way, the twisting and untwisting of
the flexible hose can advantageously be synchronized with a
twisting and untwisting of the electric cable.
The nacelle-hub-interface advantageously comprises at least a
channel in the main shaft extending essentially along the
main shaft and a first sub-interface connecting the second
distribution sub-system to the channel. Thus, a continuous
flow of the liquid medium into the main shaft is supported.
By means of the channel in the main shaft, the liquid medium
can be transported further through the wind turbine towards
the hub.
In a further preferred embodiment, the first sub-interface
comprises at least a first duct extending radially from an
outer wall of the main shaft to the channel and a housing
which encloses the main shaft annularly at an emersion
position of the first duct at which the first duct intersects
the outer wall of the main shaft. The housing is sealed
against the main shaft and comprises a channel system through
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which the liquid medium from the pipe of the second
distribution subsystem into the first duct during operation
of the liquid distribution system. For example, the channel
system in the housing may comprise an annular groove in the
5 inner wall of the housing at the emersion position of the
duct in the main shaft and a bore running radially from the
grove to a junction at which a pipe of the second
distribution sub-system may be connected. Alternatively or
additionally the shaft may also comprise an annular groove on
its outer side at the emersion position of the duct in the
main shaft. Sealings between the housing and the main shaft
may be on either side of the groove along an axial direction
of the main shaft. Thus, an effective and safe transfer of
the liquid medium from the pipe of the second distribution
sub-system into the channel is enabled. Preferably, the
housing of the first sub-interface is sealed to the rotating
main shaft by means of a number of labyrinth seals. Using
this reliable kind of conventional sealing, any loss or
spilling of liquid medium at an intersection between the non-
rotating housing and the rotating main shaft is minimized to
an extent as much as possible. In a preferred embodiment, the
main shaft is hollow alongside its longitudinal axis and the
channel in the main shaft is a pipe or a tube. In this way, a
comfortable guidance element in the form of a tube or a pipe
for the liquid medium can be realized inside the main shaft
and can easily be replaced or renewed. Also, by preventing a
physical contact between the main shaft and the liquid
medium, a possible harmful (e.g. chemical) contact between
the liquid medium and a material of the main shaft can be
avoided in this manner.
The first sub-interface advantageously comprises several
first ducts as well as several channels. Accordingly, the
housing may comprise also several bores and the housing
and/or the main shaft may comprise several grooves at the
emersion positions of the duct, each sealed against each
other. In this way, different types of liquid media with
different properties can be transported into the main shaft
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and onwards to the hub. Consequently, a further
diversification of the liquid medium distribution system is
facilitated. Also, an enhanced volumetric flow rate of the
liquid medium through the main shaft is made possible in this
manner.
The channels in the main shaft, in particular when they are
realized in form of pipes or tubes, may be extended into the
hub to build at least part of the third distribution sub-
system in the hub. However, the nacelle-hub-interface may
further comprise a second sub-interface connecting the
channel in the main shaft to the third distribution sub-
system via appropriate junctions.
Preferably, the second sub-interface comprises at least a
second duct arranged in the hub, wherein the second duct is
connected to the channel in the main shaft. A straightforward
extension for the liquid medium from the channel in the main
shaft into the hub is provided in this way. The second duct
can be dimensioned separately in a quantitative and
qualitative respect, for example as regards a number of
second ducts or a physical diameter of the second duct, which
should correspond to a physical diameter of the channel in
the main shaft. A preferred essentially coaxial orientation
of the second duct with respect to the channel in the main
shaft allows an easy manufacture of the second duct, e.g. in
a standardized milling process.
A further preferred embodiment of the wind turbine according
to the invention is characterized in that a hub-blade-
interface is provided in the hub, which hub-blade-interface
connects the third distribution sub-system to a fourth
distribution subsystem being located in at least one of the
blades. In this manner, a further extension of the flow of
the liquid medium is enabled into at least one of the blades,
for example to provide a defrosting system in the blades with
a defrosting liquid. Needless to say, depending on specific
requirements, the fourth distribution sub-system can be
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arranged in alone or more of the blades of the wind turbine.
The fourth distribution sub-system comprises a pipe and
optionally at least one of the following items: a pump, a
reservoir, a valve for accessing the liquid medium, an exit
opening for the liquid medium. Thus, as already described for
the first, the second and the third distribution sub-system,
a useful diversified design of the fourth distribution sub-
system is facilitated.
Other objects and features of the invention will become
apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely
for the purposes of illustration and not as a definition of
limitations of the invention.
Fig. 1 shows a schematic representation of an embodiment of a
wind turbine according to the invention; and
Fig. 2 shows in greater detail a schematic representation of
a nacelle-hub-interface in a wind turbine according to Figure
1.
In the drawings, like reference numbers refer to like objects
throughout. Objects in the drawings are not necessarily drawn
to scale.
Fig. 1 shows an embodiment of a wind turbine according to the
present invention. The wind turbine 100 comprises a tower 1,
a nacelle 3 being rotatable supported by the tower 1, and a
hub 4 being rotatable supported by the nacelle 3. Blades 5
are arranged on and fixed to the hub 4. The mentioned
elements are conventional elements of a wind turbine 100 and
will as such thus not be illustrated in more detail
hereinafter. Furthermore, a normal operation of the wind
turbine 100 is not in the focus of the invention and will
thus also not be described in detail hereinafter. Only those
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items, elements and systems that are relevant to the
invention will be elucidated in the following description.
Inside or outside (not shown) of the tower 1 is a source 2,
2a of liquid. Though explicitly two sources 2, 2a are shown
in Fig. 1, it is possible that only one or more than two
sources 2, 2a are arranged in the context of the invention.
The term "source" is used generically in the context of this
application, i.e. a point from which liquid is fed into the
liquid distribution system of the wind turbine 100. The term
"liquid medium" in the context of the application is
preferably any liquid medium which, for example, can be used
for lubricating and/or heating and/or defrosting any parts of
the wind turbine 100. As an option, the liquid medium could
also be used for cooling purposes. As a further option, the
liquid medium could also be a hydraulic fluid used for a
mechanical adjustment of different items of the wind turbine
100, for example for an adjustment of an angle of approach of
the blades 5. Of course, any liquid media not having been
explicitly mentioned above which are appropriate to be used
in a wind turbine 100 are also intended to fall into the
scope of the invention.
As an example, in the diagrams the type of liquid medium in
the source 2a is different from a type of liquid medium in
the source 2. Hence, advantageously, the liquid media
distribution system can be operated with different liquid
media in order to fulfil requirements which can only be
performed with different types of liquid media. To
illustrate, the liquid medium in source 2 is, for example,
lubrication fluid for greasing any items. In contrast
thereto, the liquid medium in source 2a is, for example, a
liquid medium for defrosting of the blades 5 of the wind
turbine 100.
Pipes 11, l la, 111, 11a' , 11", ila'', 11''', l1a" ' are
provided in the tower 1, in the nacelle 3, in the hub 4 and
in the blades 5 as basic guidance elements in order to
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transport the liquid medium within the whole wind turbine 100
in a well-defined way. Furthermore, several additional
conventional elements are provided in the context of the
invention, for the sake of performing element-specific
different purposes.
A first distribution sub-system 10 is arranged in the tower 1
and comprises here two pipes 11, lla through which the the
liquid medium is transported from the sources 2, 2a.
Furthermore, the first distribution sub-system 10 comprises
optionally, and only if required, one or more further items.
As an example, pumps 13, 13a are provided in order to pump
the liquid medium at defined pumping-locations in the wind
turbine 100. The number of the pumps 13, 13a can be chosen
according to various parameters, such as a power consumption
of the pumps 13, 13a, a specific weight of the liquid medium
to be pumped, the pressure which is needed etc. Further,
optionally, at least one heat exchanger 14 can be arranged
within the tower 1 in order to heat and/or to cool the liquid
medium itself, and/or to heat and/or to cool any components,
for example a gearbox or a generator 80, in the wind turbine
100. As a further option, one or more valves 15 can be added
to the system in order to regulate a flow of the liquid
medium. Moreover, one or more reservoirs 12 can optionally be
added to the system in order to store or access the liquid
medium on its way through the wind turbine 100. For example,
a number of the reservoirs 12 can be adjusted to a number of
pumps 13, 13a in the system. As a further option, a number of
reservoirs 12 and/or valves 15 can be adjusted to a number of
locations in the tower 1, where access to the liquid medium
is desired.
The pipes 11, lla can be made of rigid material such as PVC,
or, alternatively, of flexible hoses. Flexible hoses more
easily accommodate movements of the tower 1. Rigid pipes, 11,
lla, on the other hand, could be used in a structure similar
to rigid bus-bar systems, which are conventionally used for
transporting electric power in the tower 1. A combination of
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rigid and flexible pipes 11, lla is possible. Connection
means for those two different types of pipes 11, lla are
commercially available.
5 The wind turbine 100 further comprises a liquid medium
distributing interface between the tower 1 and the nacelle 3.
This specific interface is hereinafter called tower-nacelle-
interface 20, 20a. The tower-nacelle-interface 20, 20a
preferably comprises one or more flexible hoses, which are
10 arranged similar to a cable loop of electric cables 31
running from a generator 80 in the nacelle 3 into the tower
1. The electric cables 31 are used to establish a flexible
connection between the tower 1 and the nacelle 3. A specific
benefit of the tower-nacelle-interface 20, 20a - in addition
to its ability to transfer liquid medium from the tower 1
into the nacelle 3 and vice versa - lies in the fact that a
number of permissible twists of the flexible hoses of the
pipe 11, lla is matched to a number of twists for which the
electric cables 31 are designed. For this purpose, an amount
of sag of the flexible hoses is dimensioned in accordance to
an amount of sag of the electric cables 31. A conventional
twist sensor (not shown) detects a defined and permissible
amount of rotations of the nacelle 3 and - when this number
is reached - initiates a backwards rotation of the nacelle 3
in an opposite direction to an initial position. In this way,
the electric cables 31 and the flexible hoses of the pipes
11, lla are untwisted synchronously.
In the nacelle 3 several components, e.g. a frequency
converter, a generator, a gearbox may be arranged in
proximity to the liquid distribution system. In Fig. 1 only a
generator 80 is shown, representative for all other usual
components. Moreover, a second liquid media distribution sub-
system 30 is arranged in the nacelle 3 having pipes 11', lla`
and optionally at least one of the following items: a
reservoir 12', a pump 13', a heat exchanger 14' and a valve
15'. Functions of those optional items are similar as having
been described above in the context of the first distribution
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sub-system 10 in the tower 1 and will therefore, for the sake
of conciseness, not be elucidated in more detail here. The
pipes 11', 11a' in the nacelle may be attached to the pipes
11, lla in the tower via suitable connections but may also be
incorporated in the pipes 11, 11a in the tower.
In addition, the nacelle 3 comprises a nacelle-hub-interface
40 as a transition element for the flow of the liquid medium
from the nacelle 3 into the hub 4 and onwards. The nacelle-
hub-interface 40 will be later described in more detail in
the context of the description of Fig. 2. When using the
first distribution sub-system 10 and the second distribution
sub-system 30, as an option, a closed-loop configuration (not
shown) can be set up in order to circulate the liquid media
endlessly through the tower 1 and the nacelle 3. Also in this
context, of course, one, several, or any of the reservoir 12,
pump 13, heat exchanger 14 and valve 15 can be arranged in a
desired quantity and location. In other words, arrangements
and quantities of the mentioned items in Fig. 1 are
understood to be merely illustrative and by no means
restrictive.
The wind turbine 100 further comprises a hub 4, which is
fixed to the nacelle 3, more specifically, to a rotating main
shaft 41 in the nacelle 3. A third distribution sub-system 50
is arranged inside the hub 4. The third distribution-
subsystem 50 comprises, in addition to a pipe 11" (only
shown in Figure 2), optionally at least a pump 13" and/or a
reservoir (not shown) and/or a valve (not shown).
Via hub-blade-interfaces 70, which serve as transition
elements between the third liquid distribution sub-system 50
in the hub 4 and a fourth liquid distribution sub-system 60
in the blades 5, the liquid medium is distributed into at
least one of the blades 5.
The blades 5 are mounted to the hub 4. Inside at least one of
the blades 5 there can preferably be arranged a fourth
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distribution sub-system 60. The fourth distribution sub-
system 60 comprises at least a pipe 11... and optionally, if
desired, at least one of the following items: a reservoir
12''', a pump 13''', a heat exchanger (not shown), and a
valve 15'''. Furthermore, preferably, one or several exit
openings 61 for the liquid medium can be arranged on a shell
or skin of a blade 5. The exit openings 61 allow a defined
exit of the liquid medium in order to be used on the exterior
of the blades 5, e.g. as a defrosting medium for defrosting
the blades 5 in order to optimize aerodynamical properties of
the blades 5. Should the blades 5 be thickly coated with ice,
such a defrosting can advantageously prevent a shutdown of
the wind turbine 100 and thus contribute to an uninterrupted
generation of electric power. The exit openings 61 can be
realized in the form of nozzles.
Functions of the third distribution sub-system 50 and the
fourth distribution sub-system 60 are similar to a function
of the first distribution sub-system 10 which has already
been illustrated and will thus not be described in more
detail hereinafter.
Fig. 2 is an enlarged view which shows in more detail the
nacelle-hub-interface 40. The nacelle-hub-interface 40
comprises a housing 43 which is similar to a housing of a
main bearing and which annularly encloses a main shaft 41 of
a drive train of the wind turbine 100. The housing 43
comprises a channel system 430 to allow the liquid media to
transfer from pipes 11 lla' of the second distribution sub-
system 30 through first ducts 42, 42a into channels 47, 47a
running axially in the main shaft 41.
To connect each of the pipes 11, lla to its corresponding
first duct 42, 42a the channel system 430 comprises two
separate annular grooves 432, 434 in the inner wall of the
housing 43 for each duct 42, 42a at a emersion or exit
position of the respective first duct 42, 42a at which the
first duct 42, 42a intersects the outer wall of the main
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shaft 41. The annular grooves 432, 434 are connected to the
pipes 11, lla via bores 431, 433 running radially from the
grove to a junction at which the respective pipe 11, lla may
be connected. The connection between the pipes 11', 11a' and
the bores 431, 433 in the housing 43 can preferably be
annularly sealed by means of sealings 44. The sealings 44
can, for example, be O-rings (e.g. according to DIN 3771). As
an alternative, in case that the connection between the pipe
11 lla' and the housing 43 is made as a planed screwed
flange connection (not shown), sealings 44 are dispensable.
Similar to a main bearing, the housing 43 is adequately
sealed to prevent any loss or spilling of liquid media on its
way into the main shaft 41. In particular, the annular
grooves 432, 434 for the first ducts 42, 42a have to be
regional displaced on the main shaft 41, as shown in Fig. 2
and have to be sealed against each other and against the
outer surrounding, for example, by means of labyrinth seals
45. Labyrinth seals 45 as such are well known and allow a
very efficient sealing between rotating and non rotating
elements.
The first ducts 42, 42a are preferably arranged radially
extending from an outer wall of the main shaft 41 towards the
channels 47, 47a. The first ducts 42, 42a can either be
arranged substantially perpendicular (first duct 42) or
inclined (first duct 42a) to a longitudinal axis of the main
shaft 41. Needless to say, more than two first ducts 42, 42a
can be arranged in the main shaft 41. As an example of a
production of the first ducts 42, 42a, the first ducts 42,
42a can be drilled into the main shaft 41.
In a preferred embodiment, the channels 47, 47a are tubes or
pipes inside a hollow main shaft 41, wherein the main shaft
41 is hollow extending along a longitudinal axis of the main
shaft 41 (not shown). In this case, the channels 47, 47a may
be connected to the first ducts 42, 42a by appropriate
junctions at the inner wall of the hollow main shaft. Of
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course, a diameter of such hollow main shaft 41 can
advantageously be dimensioned to specific needs.
During operation of the liquid medium distribution system,
the liquid medium passes through the housing 43 and enters
the channels 47, 47a in the main shaft 41 via the first ducts
42, 42a. The path of the liquid flow inside the channels 47,
47a is indicated by arrows.
The main shaft 41 is fastened to the hub 4, e.g. by means of
several bolts 46. Second ducts 48, 48a being arranged in a
flange of the hub 4 allow a transition of the liquid medium
from the channel 47, 47a into the hub 4.
As a consequence, the liquid media exit the main shaft 41 and
enter further pipes 11'', lla '' being arranged inside the hub
4. To this end, the pipe 11'' in the hub 4 can be a separated
pipes 11' lla " are attached to the second ducts 48, 48a
via appropriate junctions. Thereby, the second ducts 48, 48a
are sealed at the junctions by annularly arranged seals 44.
As an alternative, in case the connection between the hub (4)
and the main shaft 41 is made as a planed screwed flange
connection (not shown), seals 44 are not strictly necessary.
The pipes 11", lla " in the hub 4 could also be integrally
with the above mentioned tubes or pipes (building the
channels 47, 47a) in the hollow main shaft 41, for example
extending through the second ducts 48, 48a. In this case, a
need for sealing the second duct 48, 48a with a seal 44 is
eliminated.
To summarize, the invention proposes a wind turbine with a
liquid medium distribution system which allows a diversified
transport and usage of liquid medium in the wind turbine.
Though not shown in the drawings, e.g., the transport of the
liquid medium can be performed continuously with a starting
and ending point in any of the sources 2, 2a. Numerous
advantageous variations and modifications of the invention
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are possible. As an example, one kind of liquid medium
distribution is performed in a kind of one-way transport (for
defrosting of the blades). Further, for example, liquid oils
for a use in gearboxes, bearings or hydraulic systems of the
5 wind turbine 100 can be transported in order to perform
liquid-specific tasks with components, eg. the generator 80,
of the wind turbine 100. Indeed, by a simple addition of the
mentioned optional elements, an easy and comfortable
customization of the liquid distribution system is supported
10 in order to meet various requirements and purposes.
Therefore, although the present invention has been disclosed
in the form of preferred embodiments and variations thereon,
it will be understood that numerous additional modifications
15 and variations could be made thereto without departing from
the scope of the invention. For example, the fluid
transported through the distribution system may not only be
transported to the hub and/or the blades but may also
(partially) be used for components in the nacelle, e.g. the
gearbox. For the sake of clarity, it is to be understood that
the use of "a" or "an" throughout this application does not
exclude a plurality, and "comprising" does not exclude other
steps or elements. A "unit" or "module" or "item" or
"element" or "sub-system" or "system" can comprise a number
of units or modules, or items, or elements or sub-systems or
systems unless otherwise stated.
